Epithelialization methods, dressings, and systems

ABSTRACT

Methods, dressings, and systems for promoting epithelialization of a wound or other tissue are presented. The methods, dressings, and systems help form simulated rete pegs. In one instance, an epithelialization dressing is disclosed that may include a dressing body having a plurality of projections. A plurality of apertures is formed on a portion of the dressing body. The dressing helps manage fluids on the wound and the projections form cavities into which epithelial tissue migrates to from epithelial columns that function like rete pegs. Other dressings, methods, and systems are disclosed.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/325,505, filed Jul. 8, 2014, which is a continuation of U.S. patentapplication Ser. No. 13/045,663, filed 11 Mar. 2011, now U.S. Pat. No.8,808,258, which claims the benefit, under 35 USC § 119(e), of U.S.Provisional Patent Application No. 61/314,274, entitled “PatternedNeo-Epithelialization Dressings, Systems, and Methods,” filed 16 Mar.2010, and U.S. Provisional Patent Application No. 61/314,236, entitled“Epithelialization Methods, Dressings, and Systems,” filed 16 Mar. 2010,each of which is incorporated herein by reference for all purposes.

BACKGROUND

The disclosure herein relates generally to medical wound care systems,and more particularly, to epithelialization methods, dressings, andsystems using reduced pressure.

Depending on the medical circumstances, reduced pressure has been usedfor, among other things, reduced-pressure therapy to encouragegranulation at a tissue site. In the normal healing process of a wound,epithelialization (or re-epithelialization since epithelium is actuallygrowing to replace lost epithelium) takes place after granulation andcan present a number of issues.

SUMMARY

According to an illustrative, non-limiting embodiment, a method fortreating a wound having granulation tissue in a wound bed includes thesteps of deploying an epithelialization dressing proximate thegranulation tissue in the wound bed, causing a compression force on theepithelialization dressing such that a plurality of projections impingeupon the granulation tissue, and allowing sufficient time for epitheliumtissue to form proximate the projections. The epithelialization dressingincludes a dressing body and the plurality of projections. Eachprojection has a proximal end and a distal end, and the proximal end iscoupled to a second, tissue-facing side of the dressing body.

According to another illustrative, non-limiting embodiment, a method forpromoting healing of a wound having a wound bed includes the steps offorming granulation tissue in the wound bed with a system to promotegranulation, creating a plurality of cavities in the granulation tissuewith an epithelialization dressing, and creating a plurality ofepithelial columns as epithelial tissue migrates into the cavities. Theepithelialization dressing includes a plurality of projections thatcreate the plurality of cavities in the granulation tissue.

According to another illustrative, non-limiting embodiment, a method offorming simulated rete pegs in a wound between granulation tissue andepithelium includes providing a plurality of projections, placing theplurality of projections proximate to the granulation tissue, causingthe plurality of projections to impinge upon the granulation tissue, andallowing sufficient time for epithelial migration around the pluralityof projections whereby simulated rete pegs are formed. The simulatedrete pegs help anchor adjacent tissue layers.

According to another illustrative, non-limiting embodiment, anepithelialization dressing for forming anchor points between twoadjacent tissue layers includes a dressing body and a plurality ofprojections. The dressing body has a first side and a second,tissue-facing side. Each projection has a proximal end and a distal end,and each proximal end is coupled to the second, tissue-facing side ofthe dressing body. The epithelialization dressing further includes afirst plurality of apertures formed on a portion of the dressing bodyand sub-features formed on the distal end of each of the plurality ofprojections.

According to another illustrative, non-limiting embodiment, a system forpromoting epithelialization of a wound includes an epithelializationdressing, a sealing member for forming a fluid seal over the wound andepithelialization dressing, a reduced-pressure interface for providingreduced pressure to the epithelialization dressing, and areduced-pressure source fluidly coupled to the reduced-pressureinterface. The epithelialization dressing includes a dressing body and aplurality of projections. The dressing body has a first side and asecond, tissue-facing side. Each projection has a proximal end and adistal end. Each proximal end is coupled to the second, tissue-facingside of the dressing body. The dressing body also has a plurality ofapertures formed on a portion of the dressing body and sub-featuresformed on the distal end of each of the plurality of projections.

According to another illustrative, non-limiting embodiment, a method ofmanufacturing an epithelialization dressing includes forming a dressingbody, having a first side and a second side, from a medical-gradepolymer, and forming a plurality of projections from a medical-gradepolymer with an aspect ratio (longer dimension for an averageprojections of the plurality of projections divided by a shorterdimension for the average projection of the plurality of projections) inthe range of 1/10 to 10. The projections are formed with an interiorportion and a plurality of pores that fluidly couple the interiorportion and an exterior portion of the projection. The method furtherincludes coupling the plurality of projections to the second side of thedressing body.

According to another illustrative, non-limiting embodiment, anepithelialization dressing for promoting epithelialization of a woundincludes a substantially planar member formed from a medical-gradepolymer and having a first side and a second, tissue-facing side andformed with a plurality of apertures operable to allow fluidcommunication between the first side and the second, tissue-facing side.The epithelialization dressing further includes a plurality of pegscoupled to the second, tissue-facing side. The pegs of the plurality ofpegs have a longitudinal length in the range of 10 to 5000 microns andhave an aspect ratio (longer dimension for an average peg of theplurality of pegs divided by a shorter dimension for the average peg ofthe plurality of pegs) in the range of 1/10 to 10.

Other features and advantages of the illustrative embodiments willbecome apparent with reference to the drawings and detailed descriptionthat follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, perspective view of an illustrative, non-limitingembodiment of an epithelialization dressing;

FIG. 2 is a plan view of a portion of the epithelialization dressing ofFIG. 1 showing a distal end of a projection;

FIG. 3 is a schematic, cross-sectional view of a portion of theepithelialization dressing of FIG. 1;

FIG. 4 is a schematic, cross-sectional view of an illustrativeprojection of an illustrative epithelialization dressing showing asupply reservoir;

FIG. 5 is a schematic, cross-sectional view of an illustrativeprojection of an illustrative epithelialization dressing;

FIG. 6 is a schematic, plan view of an illustrative projection of anillustrative epithelialization dressing;

FIG. 7 is a schematic, cross-sectional view of an illustrativeprojection of an illustrative epithelialization dressing;

FIG. 8 is a schematic, perspective view of an illustrativeepithelialization dressing;

FIG. 9 is a schematic diagram with a portion shown in cross section ofan illustrative system for promoting granulation;

FIG. 10 is a schematic diagram with a portion shown in cross section ofan illustrative system for promoting epithelialization; and

FIG. 11 is a schematic, cross-sectional view of a wound that has beentreated to promote epithelialization with an epithelialization dressingaccording to one illustrative embodiment.

DETAILED DESCRIPTION

In the following detailed description of the non-limiting, illustrativeembodiments, reference is made to the accompanying drawings that form apart hereof. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it isunderstood that other embodiments may be utilized and that logicalstructural, mechanical, electrical, and chemical changes may be madewithout departing from the spirit or scope of the invention. To avoiddetail not necessary to enable those skilled in the art to practice theembodiments described herein, the description may omit certaininformation known to those skilled in the art. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the illustrative embodiments are defined only by the appendedclaims.

The outermost, or most superficial, layer of skin is the epidermis,which itself has numerous layers. The epidermis is adjacent to thedermis. The epidermis may have inwardly directed prolongations of theMalpighian layer that intermesh with the dermal papillae. Theseprolongations are sometimes called “rete pegs.” The rete pegs mayprovide resistance against shear-induced separation of adjacent layers.In contrast, reepithelialized wounds often do not have as muchresistance against shear.

In the healing process of wounds, the epidermis may regenerate, but thenewly formed epithelium often, at least initially, lacks rete pegs. Assuch, the newly formed epithelium may be easily disrupted or sloughedoff. Referring now primarily to FIGS. 1-3, an epithelialization dressing100 may be used to promote a stronger connection or tethering of layersso as to function effectively as healthy rete pegs. Theepithelialization dressing 100 may induce anchor points of epitheliumwith tissue layers underlying the epidermis by using surfacearchitecture on the epithelialization dressing 100.

Moreover, the epithelialization dressing 100 may hold or secure theepithelium with underlying tissues and thereby protect the epitheliumfrom shear force damage. In addition, the epithelialization dressing 100may maintain a barrier and obviate the need for repeated repair of theepithelium. The epithelialization dressing 100 may also speed theepithelialization process.

The epithelialization dressing 100 may carry out numerous functions. Forexample, the epithelialization dressing 100 may function to help managefluids at a wound to promote epithelialization. As another example, theepithelialization dressing 100 may use physical, chemical, or mechanicalproperties of the epithelialization dressing 100 to direct developmentof underlying tissue structures to facilitate strength of theregenerated epidermis. As used herein, unless otherwise indicated, “or”does not require mutual exclusivity.

The epithelialization dressing 100 may be formed with a dressing body102 having a first side 104 and a second, tissue-facing side 106. Thedressing body 102 may take numerous shapes, but is shown as a laminarbody, i.e., having an aspect ratio (longer dimension divided by shorterdimension) greater than one in both a longitudinal cross section andlateral cross section. In other words, the dressing body 102 is shown asa flat or substantially flat member. Other shapes may be used for thedressing body 102, such as a rounded member.

The dressing body 102 has a plurality of projections 108 that may becoupled to the second, tissue-facing side 106 of the dressing body 102.Each projection 108 has a proximal end 110 and a distal end 112. Theproximal end 110 of each projection 108 is coupled to the second,tissue-facing side 106 of the dressing body 102. A plurality ofapertures 114, such as slits 116 or fenestrations, may be formed on aportion of the dressing body 102. The apertures 114 may be slits 116(longitudinal openings with substantially no material removed) or may beround holes, square holes, or openings of any shape that provide for thetransfer of fluids including reduced pressure.

The projections 108 or other micro-features are for placing ongranulation tissue and function to help form epithelium columns 166(FIG. 11) that may function like rete pegs. The projections 108 may takenumerous shapes and sizes. The projections 108 may be for example rods,cones, columns, ridges, grooves, waves, or other features that formcavities 162 (FIG. 10). For example, FIGS. 1-5 present projections 108as conical members, FIG. 6 presents projections 108 that are triangularin plan view, and FIG. 7 presents a cross section of projections 108 ascylindrical members. FIG. 8 presents a perspective view showingprojections 108 that are formed like continuous bars or orthogonalmembers. The projections 108 may be randomly spaced or spaced with apattern on the dressing body 102. As shown in FIG. 5, the projectionsmay have a supply reservoir 117 formed within.

Referring now primarily to FIG. 3, each projection 108 may have alongitudinal length 118 (measured from the second, tissue-facing side106) and a lateral width or diameter 120 at the proximal end 110 andlateral width or diameter 122 at the distal end 112. Each projection 108may have an aspect ratio (longitudinal length 118/average lateral width)that is in the range of 1/10 to 10 and more typically ½ to 2. Theaverage projection of the plurality of projections 108 may have anaspect ratio (longer dimension for an average projections of theplurality of projections divided by a shorter dimension for the averageprojection of the plurality of projections) in the range of 1/10 to 10and more typically ½ to 2. In other non-limiting examples, the aspectratio may be 3/10, 5/10, 8/10, 2, 3, 4, 5, 6, 7, 8, or 9. The aspectratio may be adjusted to help control the level of strain placed onunderlying tissue and to help control strain gradients. Controlling theinduced strain may help control remodeling of the tissue and may impactstem cell differentiation. An edge 124, or leading edge, on the distalend 112 of the projection 108 may be sharp (orthogonal, 90 degrees, orsubstantially 90 degrees) or may be rounded to help control strain aswell. The projections 108 may all have the same dimensions or propertiesor may vary one to another.

As shown in FIG. 2, a plurality of pores 126 or small apertures may beformed on the distal end 112 of the projections 108. The pores 126 mayalso or alternatively be formed at other locations on the projections108 or dressing body 102. The pores 126 may facilitate removal of fluidsnear the epithelialization dressing 100, deliver reduced pressure, allowfor fluid delivery, or provide for intentional ingrowth of tissue. Pores(not shown) may also be formed on the second, tissue-facing side 106 ofthe dressing body 102 between the projections 108. With reference toFIG. 4, the pores 126 may help deliver a fluid or other substance, e.g.,growth factors, from the supply reservoir 117 to an area near theprojection 108.

Referring primarily to FIG. 5, the pores 126 are shown facilitating thedelivery of reduced pressure and the removal of fluids near theprojections 108. Apertures 115 through the dressing body 102 allowreduced pressure to be delivered from the first side 104 of the dressingbody 102 to the supply reservoir 117. The pores 126, which in thisembodiment are on the distal end and on a side portion of the projection108, communicate the reduced pressure from the supply reservoir 117 toan exterior of the projections 108. In this embodiment, the first side104 of the dressing body 102 is in fluid communication with an exteriorof the projections 108. In another embodiment, the projections 108 maybe formed with a bicameral reservoir (not shown) having one portion forsupplying a substance and another portion for providing reducedpressure.

As shown in FIG. 6, in some embodiments, micro-scale or nano-scalefeatures 128, or sub-features, may be added to the projections 108typically on the distal end 112. The sub-features 128 may be, forexample, grooves 130, ridges, or waves. The sub-features 128 aretypically separate from the pores 126, but in other embodiments, couldinclude openings as the pores on the sub-features 128. The micro-scaleor nano-scale features 128 may be able to pattern proteins that absorbto the sub-features 128 or promote cell height and direct orientationand migration. If the sub-features 128 are grooves, e.g., the grooves130, fibroblasts may attach and become oriented according to thefeatures and secrete their matrix proteins in a similar pattern. Thismay further allow control of tissue development.

The size and shape of the projections 108, the size and spacing of thepores 126, or the sub-features 128 may be used to control the tissuedevelopment in order to promote maturation and to enhance the strengthof a healing wound against shear stress. The projections 108 or othermicro-features may guide tissue growth and remodeling, includingcellular orientation and organization. Geometry of the projections 108or micro-features may be modulated to induce specific load and straindistribution and gradients in the tissue. These modulations may involveaspect ratio, size, spacing, contact area (%), curvature at contact,alternating feature shapes and sizes, biomimetic patterns, and theoverlay of micro and sub-features 128. The size and aspect ratio of theprojections 108 may be modulated as desired to control stress and strainat the tissue interface.

Numerous materials may be used to form the epithelialization dressing100, such as a medical-grade polymer, e.g., a silicone or polyurethane,or a biological polymer, e.g., collagen. Other materials from which theepithelialization dressing 100 may be formed include bioresorbable (orresorbable) material, biologic material, or non-resorbable material. Asused herein, “bioresorbable” includes a material that enzymatically orchemically degrades into a simple chemical species in vivo, and whichmay be removed from the body by excretion or metabolism. The materialmay be an occlusive material. The epithelialization dressing 100 may benon-adherent to tissue growth. The epithelialization dressing 100 may beformed from a non-absorbable material for the dressing body 102. Theprojections 108 may be formed from a bioresorbable material. In anotherembodiment, the entire epithelialization dressing 100 is formed frombioresorbable material. The second, tissue-facing surface 106 of theepithelialization dressing 100 may be a moist surface that—other thanthe projections 108—is relatively smooth as compared to a foam surface.With reference to FIG. 3, the dressing 100 may have a depth 132 that isin the range of 10 to 5000 microns, and more typically between 400 and600 microns. For example, without limitation, the depth 132 may be 400,425, 450, 475, 500, 525, 550, 575, 600 microns or another depth.

Referring now to FIG. 8, another illustrative, non-limiting embodimentof an epithelialization dressing 100 is presented. The epithelializationdressing 100 of FIG. 8 may be formed with a dressing body 102 having afirst side 104 and a second, tissue-facing side 106. A plurality ofprojections 108 may be coupled to the second, tissue-facing side 106 ofthe dressing body 102. Each projection 108 has a proximal end 110 and adistal end 112. The proximal end 110 of each projection 108 is coupledto the second, tissue-facing side 106 of the dressing body 102. Theprojections 108 form a grid that is used to impinge upon granulationtissue. A plurality of apertures 114 are formed on a portion of thedressing body 102 and are shown as circular openings.

Referring now primarily to FIGS. 9-11, one illustrative, non-limitingprocess for treating a wound 134 or other tissue site is presented.Referring initially to FIG. 9, the wound 134 is treated with a system103 to promote granulation. A manifold 136 is disposed proximate thewound 134. The term “manifold” as used herein generally refers to asubstance or structure that is provided to assist in applying reducedpressure to, delivering fluids to, or removing fluids from a tissue siteor wound 134.

The manifold 136 typically includes a plurality of flow channels orpathways that distribute fluids provided to and removed from the tissuesite or wound 134 around the manifold 136. In one illustrativeembodiment, the flow channels or pathways are interconnected to improvedistribution of fluids provided or removed from the wound 134. Themanifold 136 may be a biocompatible material that is capable of beingplaced in contact with wound 134 and distributing reduced pressure tothe wound 134.

Examples of manifolds 136 may include, for example, without limitation,devices that have structural elements arranged to form flow channels,such as, for example, cellular foam, open-cell foam, porous tissuecollections, liquids, gels, and foams that include, or cure to include,flow channels. The manifold 136 may be porous and may be made from foam,gauze, felted mat, or any other material suited to a particularbiological application. In one embodiment, the manifold 136 is porousfoam and includes a plurality of interconnected cells or pores that actas flow channels. The porous foam may be a polyurethane, open-cell,reticulated foam, such as V.A.C.® GranuFoam® material manufactured byKinetic Concepts, Incorporated of San Antonio, Tex. Other embodimentsmay include “closed cells.” In some situations, the manifold 136 mayalso be used to distribute fluids such as medications, antibacterials,growth factors, and various solutions to the wound 134. Other layers maybe included in or on the manifold 136, such as absorptive materials,wicking materials, hydrophobic materials, and hydrophilic materials.

A reduced-pressure interface 138, e.g., a connector, is disposedproximate the manifold 136 and extends through an aperture 140 in asealing member 142. The sealing member 142 forms a fluid seal over thewound 134. “Fluid seal,” or “seal,” means a seal adequate to maintainreduced pressure at a desired site given a particular reduced-pressuresource or subsystem involved.

The sealing member 142 may be any material that provides a fluid seal.The sealing member may, for example, be an impermeable orsemi-permeable, elastomeric material. “Elastomeric” means having theproperties of an elastomer. Elastomeric material generally refers to apolymeric material that has rubber-like properties. More specifically,most elastomers have ultimate elongations greater than 100% and asignificant amount of resilience. The resilience of a material refers tothe material's ability to recover from an elastic deformation. Examplesof elastomers may include, but are not limited to, natural rubbers,polyisoprene, styrene butadiene rubber, chloroprene rubber,polybutadiene, nitrile rubber, butyl rubber, ethylene propylene rubber,ethylene propylene diene monomer, chlorosulfonated polyethylene,polysulfide rubber, polyurethane (PU), EVA film, co-polyester, andsilicones. Additional, specific examples of sealing member materialsinclude a silicone drape, a 3M Tegaderm® drape, or a polyurethane (PU)drape such as one available from Avery Dennison Corporation of Pasadena,Calif. The sealing member 142 has a first side 144 and a second,tissue-facing side 146.

An attachment device 148 may be used to hold the sealing member 142against the patient's epidermis 150 or another layer, such as a gasketor additional sealing member. The attachment device 148 may takenumerous forms. For example, the attachment device 148 may be amedically acceptable, pressure-sensitive adhesive that extends about aperiphery of the sealing member 142. As additional examples, theattachment device 148 may be a double-sided drape tape, paste,hydrocolloid, hydro gel or other sealing devices or elements.

A reduced-pressure delivery conduit 152 may fluidly couple thereduced-pressure interface 138 to a reduced-pressure source 154 thatprovides reduced pressure. The reduced-pressure source 154 may be anydevice for supplying a reduced pressure, such as a vacuum pump, wallsuction, micro-pump, or other source. While the amount and nature ofreduced pressure applied to a tissue site or wound 134 will typicallyvary according to the application, the reduced pressure will typicallybe between −5 mm Hg (−667 Pa) and −500 mm Hg (−66.7 kPa) and moretypically between −75 mm Hg (−9.9 kPa) and −300 mm Hg (−39.9 kPa). Forexample, and not by way of limitation, the pressure may be −12, −12.5,−13, −14, −14.5, −15, −15.5, −16, −16.5, −17, −17.5, −18, −18.5, −19,−19.5, −20, −20.5, −21, −21.5, −22, −22.5, −23, −23.5, −24, −24.5, −25,−25.5, −26, −26.5 kPa or another pressure.

As used herein, “reduced pressure” generally refers to a pressure lessthan the ambient pressure at a tissue site that is being subjected totreatment. In most cases, this reduced pressure will be less than theatmospheric pressure at which the patient is located. Alternatively, thereduced pressure may be less than a hydrostatic pressure at the tissuesite. Unless otherwise indicated, values of pressure stated herein aregauge pressures. The reduced pressure delivered may be constant orvaried (patterned or random) and may be delivered continuously orintermittently. Although the terms “vacuum” and “negative pressure” maybe used to describe the pressure applied to the tissue site, the actualpressure applied to the tissue site may be more than the pressurenormally associated with a complete vacuum. Consistent with the useherein, unless otherwise indicated, an increase in reduced pressure orvacuum pressure typically refers to a relative reduction in absolutepressure.

One or more devices, such as device 156, may be included on thereduced-pressure conduit 152. For example, the device 156 may be a fluidreservoir, or collection member, to hold exudates and other fluidsremoved. Other examples of devices 156 that may be included on thereduced-pressure delivery conduit 152 or otherwise fluidly coupled tothe reduced-pressure delivery conduit 152 include the followingnon-limiting examples: a pressure-feedback device, a volume detectionsystem, a blood detection system, an infection detection system, a flowmonitoring system, or a temperature monitoring system. Some of thesedevices may be formed integrally with the reduced-pressure source 154.

The reduced pressure delivered to the wound 134 helps to fill in thewound defect with new tissue. The reduced pressure may promotefibroblasts to synthesize and develop extracellular matrix components.Granulation tissue fibroblasts produce a matrix for collagen deposition.After sufficient time, granulation tissue 158 (FIG. 10) is deposited ona bed of the wound 134. After the granulation tissue 158 has adequatelydeveloped, the sealing member 142 may be removed and the manifold 136removed. In the example of FIGS. 9 and 10, the granulation tissue 158has grown outward from near or at a dermis layer 151 to above a lowerportion of the epidermis 150.

Referring now primarily to FIG. 10, a system 101 for promotingepithelialization is presented. The epithelialization dressing 100 mayplaced proximate the granulation tissue 158 with the second,tissue-facing side 106 and projections 108 substantially against thegranulation tissue 158. A sealing member 142 is then deployed to providea fluid seal over the epithelialization dressing 100. In one embodiment(not explicitly shown), the manifold 136 (see FIG. 9) may be placedbetween the epithelialization dressing 100 (see FIG. 10) and sealingmember 142 to facilitate reduced pressure distribution and fluid removalfrom wound areas distal from reduced-pressure interface 138.

Referring again to the embodiment of FIG. 10, after the reduced-pressureinterface 138 and the sealing member 142 (this includes new interfacesand sealing members) are deployed, the reduced-pressure source 154 isagain activated. The reduced pressure supplied to the epithelializationdressing 100 may achieve a number of results.

The reduced pressure delivered to the epithelialization dressing 100 mayhelp remove excess fluids from a surface 160 of the wound 134, which hasbeen partially regenerated. Some fluids may remain to assist withsignaling and to otherwise promote re-epithelialization. The reducedpressure may provide a compression force on the dressing 100 to help tomaintain and control contact between the dressing 100 and thegranulation tissue 158 or other tissue. The reduced pressure may be usedto cause or control the magnitude of force causing the projections 108to impinge on the granulation tissue 158 or other tissue. In someembodiments, the pressure may be varied (patterned or random) toprovided a variable force delivered by the epithelialization dressing100 and may thereby further enhance epithelialization.

Referring now primarily to FIGS. 10 and 11, fibroblasts may interactwith the second, tissue-facing side 106 of the dressing 100 and formpatterned extracellular matrix. Activated keratinocytes migrate from thewound edges 164 around and between the projections 108 and down into thecavities 162 formed by the projections 108 and form an epithelium 168 ornew epithelium tissue (FIG. 11). The portion of the matrix going intothe cavities 162 will gradually form epithelium columns 166, which maytake any shape corresponding substantially to the shape of theprojections 108. The epithelium 168 has an x-y pattern around theprojections 108 and a pattern in the z-direction as the epithelium 168moves into the cavities 162 to form the epithelium columns 166. Thecavities 162 formed by the projections 108 will extend into the adjacentlayer of granulation tissue 158 and help form the epithelium columns166. The epithelium columns 166 act functionally like rete pegs betweenthe epidermis 150 and dermis 151 and thereby may provide anchor pointsresistant against external forces to keep the involved tissue layersadherent. The epithelium columns 166 form simulated rete pegs.

Referring now primarily to FIG. 11, the wound 134 is shown afterdressing 100 has been removed. (The surface of the epithelium 168 may bemore or less flush with the intact epidermis 150 than shown). Thedressing 100 may stay in place on the wound for a set time of anyduration and typically between one to six days. In this illustrative,non-limiting embodiment, the epithelium 168 covers the granulationtissue 158. The epithelium columns 166 fill the cavities 162 and extendinto the granulation tissue 158. In some embodiments (not explicitlyshown), the epithelium columns 166 extend into a portion of the dermis151. The epithelium columns 166 provide additional shear resistance forthe epithelium 168.

It should be noted that while the process of FIGS. 9-11 shows the use ofreduced-pressure treatment to promote formation of the granulationtissue 158, the dressing 100 may be used independently of such a step.In addition, while the process and system 100 has been described asusing reduced pressure, it should be understood that the dressing 100may be used without reduced pressure. In this illustrative process, thedressing 100 may further include a hydrophilic material, e.g.,hydrophilic foam or capillaries, on the first side 104 to help removefluids through the apertures 114 and a bolster, tape, compression wrap,or other device may be used to provide a compression force on thedressing 100 to assure contact between the dressing 100 and the tissue.

Numerous alternatives or additions may be involved with theillustrative, non-limiting dressing 100, system 101, or the process.Some have already been mentioned and other, non-exhaustive examples arenow mentioned. In another illustrative process, the dressing 100 may bemade from a reabsorbable material that degrades. The projections 108 mayinclude supply reservoirs 117 that hold encapsulated stem cells,keratinocytes, growth factors, soluble factors, or other substance. Asthe degradation reaches a certain level, the substance within the supplyreservoirs 117 is delivered to the cavities 162 and tissue. Thesubstance then fills or helps fill the cavity 162 and helps promotefurther healing.

In another illustrative, non-limiting embodiment, the dressing 100,system 101, or the processes may be used with other tissues. Forexample, in addition to epithelial tissue, endothelial and mucosallinings may benefit. Other embodiments may also be used for treatingtendons, ligaments, muscles, or cartilage to add inherent resistance tothe forces that actively work to separate these tissues.

In another illustrative, non-limiting example, the dressing 100 may beused as an aspect of promoting granulation and epithelialization. Thedressing 100 may include the projections 108 with pores 126 on thedistal end 112 and also all along the side walls of the projections 108.Ingrowth of granulation tissue 158 into the pores 126 is promoted. Ifreduced pressure is utilized, the reduced pressure may help pull tissueinto the pores 126. Once the granulation tissue 158 has grown into andaround the projections 108, the advancing keratinocytes may follow thegranulation tissue 158 and overlay the granulation tissue 158. Inaddition or as a separate alternative, the dressing 100 may bebioresorbable and degrade over time. The degradation should notnegatively impact keratinocyte proliferation. In addition, theprojections 108 may have supply reservoirs 117 with active solublefactors that enhance local keratinocyte differentiation. The thickeningof the keratinocytes in this area may fill the cavity 162 formed by theprojections 108.

Although the present invention and its advantages have been disclosed inthe context of certain illustrative, non-limiting embodiments, it shouldbe understood that various changes, substitutions, permutations, andalterations can be made without departing from the scope of theinvention as defined by the appended claims. It will be appreciated thatany feature that is described in connection to any one embodiment mayalso be applicable to any other embodiment.

It will be understood that the benefits and advantages described abovemay relate to one embodiment or may relate to several embodiments. Itwill further be understood that reference to ‘an’ item refers to one ormore of those items.

The steps of the methods described herein may be carried out in anysuitable order, or simultaneously where appropriate.

Where appropriate, aspects of any of the examples described above may becombined with aspects of any of the other examples described to formfurther examples having comparable or different properties andaddressing the same or different problems.

It will be understood that the above description of preferredembodiments is given by way of example only and that variousmodifications may be made by those skilled in the art. The abovespecification, examples and data provide a complete description of thestructure and use of exemplary embodiments of the invention. Althoughvarious embodiments of the invention have been described above with acertain degree of particularity, or with reference to one or moreindividual embodiments, those skilled in the art could make numerousalterations to the disclosed embodiments without departing from thescope of the claims.

1. A method for treating a wound having granulation tissue in a woundbed, the method comprising the steps of: deploying an epithelializationdressing proximate the granulation tissue in the wound bed, wherein theepithelialization dressing comprises: a dressing body having a firstside and a second side, the dressing body comprising a plurality ofapertures disposed through the first side and the second side, and aplurality of projections, each projection having a proximal end and adistal end, the proximal end coupled to the second side of the dressingbody between the plurality of apertures; and causing a compression forceon the epithelialization dressing such that the plurality of projectionsimpinge upon the granulation tissue.
 2. The method of claim 1, furthercomprising: wherein the plurality of apertures provide fluidcommunication between the first side of the dressing body and the secondside of the dressing body; causing a fluid seal over theepithelialization dressing; and providing reduced pressure to theepithelialization dressing. 3.-4. (canceled)
 5. The method of claim 1,wherein at least one of the plurality of projections comprises a pore.6. The method of claim 1, wherein the plurality of projections furthercomprise supply reservoirs formed in an interior portion of theprojections.
 7. (canceled)
 8. The method of claim 1, wherein theplurality of projections further comprise supply reservoirs formed in aninterior portion of the projections and wherein the plurality ofprojections and the dressing body are formed of a bioresorbablematerial.
 9. The method of claim 1, wherein: each of the plurality ofprojections further comprises a supply reservoir formed in an interiorportion of each of the plurality of projections; a second plurality ofapertures formed on the dressing body and substantially aligning witheach of the plurality of projections to allow fluid communicationbetween the interior portion of each projection and the first side ofthe dressing body; and each of the plurality of projections having poreson the distal end, wherein the pores provide fluid communication betweenan exterior and the interior portion of the projection.
 10. (canceled)11. The method of claim 1, further comprising sub-features formed on thedistal end of the plurality of projections and wherein the sub-featurescomprise ridges.
 12. (canceled)
 13. The method of claim 1, wherein theprojections of the plurality of projections have an aspect ratio in therange of 1/10 to
 10. 14. A method for promoting healing of a woundhaving a wound bed, the method comprising the steps of: forminggranulation tissue in the wound bed with a system to promotegranulation; creating a plurality of cavities in the granulation tissuewith an epithelialization dressing, wherein the epithelializationdressing comprises a plurality of projections that create the pluralityof cavities in the granulation tissue; and creating a plurality ofepithelial columns as epithelial tissue migrates into the cavities. 15.The method of claim 14, wherein forming granulation tissue in the woundbed with a system to promote granulation comprises: deploying a manifoldproximate the wound; deploying a sealing member over the manifold andwound to form a fluid seal; and providing reduced pressure to themanifold.
 16. The method of claim 14, wherein creating a plurality ofcavities and creating a plurality of epithelial columns comprise:deploying the epithelialization dressing proximate the granulationtissue; deploying a sealing member over the epithelialization dressingand wound; providing reduced pressure to the epithelialization dressingto cause the plurality of projections to impinge upon the granulationtissue; and providing adequate time for epithelial tissue to migratearound the plurality of projections to form the plurality of epithelialcolumns. 17.-40. (canceled)
 41. A method of manufacturing anepithelialization dressing, the method comprising: forming a dressingbody, having a first side and a second side, from a medical-gradepolymer; forming a plurality of projections from a medical-grade polymerwith an aspect ratio in the range of 1/10 to 10; coupling the pluralityof projections to the second side of the dressing body; and formingapertures in the dressing body between the plurality of projections. 42.The method of manufacturing of claim 41, further comprising forming eachof the projections with an interior portion, an exterior portion, and aplurality of pores fluidly coupling the interior portion and theexterior portion.
 43. The method of manufacturing of claim 41, whereinthe steps of forming a dressing body, forming a plurality ofprojections, and coupling the plurality of projections comprise moldingthe dressing body with the plurality of projections.
 44. Anepithelialization dressing for promoting epithelialization of a wound,the dressing comprising: a substantially planar member formed from amedical-grade polymer and having a first side and a second side andformed with a plurality of apertures operable to allow fluidcommunication between the first side and the second side; and aplurality of pegs coupled to the second side between the apertures, thepegs of the plurality of pegs having a longitudinal length in the rangeof 10 to 5000 microns.
 45. (canceled)